Separate units from coordinate notation
A coordinate value needs both a unit and a way to locate its decimal point. A Gerber file normally declares millimetres or inches using MO and its fixed-point notation using FS. This viewer requires those declarations and supports absolute coordinates with the same X and Y format. It refuses missing or conflicting declarations instead of guessing from the apparent board size.
For example, X254000 in a 2:4 format means 25.4000 units. With millimetres declared, that is 25.4 mm. A coordinate of X010000 under the same format and inches means 1.0000 inch, also 25.4 mm. Equivalent layers should therefore overlap after unit conversion even though their source coordinates differ.
Check drill declarations carefully
Excellon exports vary more widely. A file with X25.400Y12.700 already contains decimal points, so those positions do not need an implied fixed-point format. Integer-only coordinates need a documented format and zero treatment. This tool reads supported FILE_FORMAT and export declarations; if required information is absent, the layer is excluded with an explanation.
The optional controls supply missing drill information only. They never replace a declaration already present in the file. Choose a setting from the PCB exporter or accompanying documentation, not from whichever setting makes the picture look familiar. Every supplied assumption appears in the report so another person can review the interpretation.
Distinguish omitted zeros from retained zeros
The form describes suppression directly: leading zeros omitted or trailing zeros omitted. Excellon LZ and TZ declarations traditionally describe retained zeros, which reverses the corresponding omission rule. Confusing these conventions can move a hole by orders of magnitude while still producing syntactically valid coordinates. Check the exporter’s documented convention when preparing a package.
Once rendered, compare a known dimension or hole spacing with the source design. An apparent 25.4-times difference suggests an inch/millimetre mismatch, but this observation alone is not permission to rewrite the source. Keep the original files and the recorded assumptions. Incremental Excellon, repeats and routed slots are outside this release; an unsupported command should prompt a different export or viewer rather than a guessed conversion.